Motor fuel compositions



3,007,783 Patented Nov. 7., 1961 ems 3,007,783 MOTGR FUEL COMPOSITEONSWilliam S. Young, Albert (1. (Condo, Jr., .lames B, Hunter, and HymanIserson, Newtown Square, Pa., assiguors of one-half to The AtlanticRefining Company, Philadelphia, Pa., a corporation of Pennsylvania, andof one-half to Pennsalt Chemicals Corporation, Philadelphia, Pa., acorporation of Pennsylvania No Drawing. Filed Nov. 18, 1958, der. No.774,596

4 Claims. (Cl. 44-69) This invention relates to improved motor fuelswhich will provide a reduced octane requirement increase and inhibitsurface ignition in internal combustion engines. The invention morespecifically relates to motor fuels in the gasoline boiling rangecontaining an organofluoro phosphorus compound.

In recent years there have been developed internal combustion enginesfor use in motor cars which because of their high compression ratiorequire fuels of exceedingly high octane number. In order to producesuch fuels economically it has been found necessary to add to thegasoline tetraethyl lead antiknock fluid in amounts ranging up to 3 cc.per gallon of gasoline. Moderately high octane number fuels have beenfound to satisfy the octane requirements of the engines while theengines are new but as the engines are used they require increasinglyhigher octane number fuels with the result that after a few months ofoperation only the very highest octane number fuels can be used in them.

This increase in octane requirement that an engine may experience duringthe whole or any part of its operating life is termed octane numberrequirement increase and is usually abbreviated to ORI. ORI has beenfound to be caused by combustion chamber deposits, which deposits it isbelieved increase the octane requirement of the engine for at least tworeasons. The deposits decrease the physical volume of the combustionchamber and thus in effect increase the compression ratio of the enginewhich in turn raises the octane number requirement of the engine. Thedeposits also have a heat insulating effect which reduces the rate ofheat transfer from the combustion chamber to the cooling system. Thiscauses excessive heat to be transferred to the incoming air-fuel mixturewhich sensitizes the mixture and promotes autoignition. Thus as theengine is operated the amount of deposits increases and the octanenumber requirement increases. Moreover, it has been suggested also thatthese deposits produce hot spots in the combustion chamber wherepreignition can occur; that is, the hot, incandescent spot in thecombustion chamber will cause the explosion of the gasoline-air mixtureinstead of the explosion being caused by the firing of the spark plug.This ignition generally occurs prior to the firing of the spark plug andhence this phenomenon is often termed preignition or surface-ignition.Preignition or surface-ignition often produces an effect similar to thatof the knocking of low octane number fuels in a high octane requirementsituation.

Heretofore gasoline additives have been devised which when used withfuels containing tetraethyl lead provide a reduction in the formation ofcombustion chamber deposits within the engine. Other additives have beendevised which when added to a fuel containing tetraethyl lead inhibitsurface ignition or preignition phenomena.

A motor fuel composition now has been found, however, whichsimultaneously will reduce the formation of combustion chamber deposits,thus preventing octane requirement increase of an engine and will alsoinhibit preignition or surface-ignition phenomena.

Accordingly it is an object of this invention to provide a motor fuelcomposition comprising a major amount of hydrocarbons boiling in thegasoline range and a minor amount of an additive which is sufficient toreduce the octane requirement increase and inhibit surface-ignition inan internal combustion engine.

It is a further object of this invention to provide a motor fuelcomposition comprising a major amount of hydrocarbons boiling in thegasoline boiling range and a minor amount suflicient to reduce theoctane requirement increase and inhibit surface-ignition in an internalcombustion engine of a organofluoro phosphorus compound.

Further objects of this invention will be apparent from the descriptionand claims that follow.

In accordance with the instant invention an organofluoro phosphoruscompound is added to gasoline in minor amounts. These compounds areadded preferably to a gasoline containing tetraethyl lead since the bulkof the gasoline presently being produced is leaded and it is theimprovement of such fuels that is the primary purpose of this invention.The tetraethyl lead antiknock agent is employed in conventional amountsand contains the usual scavenging agents. In addition the gasoline maycontain minor and conventional amounts of other additives such assolvent oils, gum inhibitors, dyes, lead stabilizers, carburetoranti-icing agents and similar additives.

The amount of organofluoro phosphorus compound which is added to thegasoline is preferably based on the amount of tetraethyl lead fluidcontained in the gasoline and is expressed as a ratio between the gramatoms of phosphorus in the organofluoro phosphorus compound to the gramatoms of lead in the tetraethyl lead fluid in the gasoline. Thepreferred ratio ranges between 0.02 and 2 gram atoms of phosphorus to 3gram atoms of lead. Since 3 cc. of tetraethyl lead fluid per gallon isequivalent to approximately 0.015 gram atom of lead per gallon theamount of phosphorus corresponding to the maximum amount of lead wouldrange between 0.0001 and 0.01 gram atom of phosphorus per gallon ofgasoline. The preferred ratio of phosphorus to lead, however, is between0.2 and 1.0 gram atom of phosphorus to 3 gram atoms of lead, while themost preferred range is 0.3 to 0.5 gram atom of phosphorus to 3 gramatoms of lead.

The organofluoro phosphorus compounds suitable for use as gasolineadditives in accordance with the instant invention have the generalformula:

Ra-O wherein R R and R are radicals selected from the group consistingof alkyl, aryl, alkaryl, aralkyl, fluoroalkyl, fluoro-alkaryl andfluoro-aralkyl radicals. The total number of carbon atoms in themolecule ranges between 3 and 30 and the total number of fluorine atomsin the molecule ranges between 2 and 15. In addition any carbon atomwhich is fluorine substituted bears at least two fluorine atoms and inthe case of terminal carbon atoms the carbon may bear three fluorineatoms. In general, these compounds are prepared by reacting afluoro-alcohol or a combination of an alcohol or phenol or substitutedphenol and a fluoro-alcohol with phosphorus oxychloride.

The preferred compound for use in conjunction with the gasolinecomponent of this invention is tris (trifluoroethyl) phosphate which hasthe following structural formula:

Other typical compounds included within the scope of this invention havestructural formulas as follows:

C FsCHzO C FaC 2OP=O CFsCHzO CFaC 2O CFsCHzO The following examples willserve to illustrate the preferred mode for carrying out the instantinvention and to further define its scope and usefulness.

EXAMPLE I Various fuel compositions were tested in a Briggs andStratton, Model S-S, single cylinder, air cooled, L-head internalcombustion engine. The base gasoline employed was a commercial premiumgasoline containing a blend of C hydrocarbons, catalytically reformednaphtha and catalytically cracked naphtha together withisobutanebutylene alkylate. This gasoline had a boiling range of 90 F.to 420 F. and contained 3 cc. of conventional tetraethyl lead fluid pergallon. The lubricant employed was a conventional premium gradedetergent-inhibitor additive lubricating oil of SAE 20 grade.

The engine was first run for 20 hours on the conventional gasoline fuelduring which time the octane requirement of the engine increased from 62to 71, i.e. an increase of 9 octane numbers. After the run the enginewas dismantled and and the interior surfaces of the combustion chamberand exhaust valve were cleaned of deposits. A new spark plug was usedfor each run.

After reassembly the engine was operated for a period of 20 hours on thesame gasoline; however, in this run the gasoline contained tris(trifiuoroethyl) phosphate in an amount corresponding to 1 gram atom ofphosphorus per 3 gram atoms of lead in the lead tetraethyl and since thelead was at the 3 cc. level this amounted to 0.005 gram atom ofphosphorus per gallon of gasoline. During this run the octanerequirement of the engine increased only 2 numbers, i.e. from 62 to 64.

7 After disassembly, cleaning and reassembly the engine was operated for20 hours on the same conventional gasoline which contained triethylphosphate in an amount corresponding to 0.005 gram atom of phosphorusper that where there are fluorine atoms in the latter compound there arehydrogen atoms in the former compound. During this run the octanerequirement of the engine increased from 62 to 71, i.e. the sameincrease as found for the blank run on the conventional fuel withoutadditive.

The engine was again disassembled, cleaned, reassembled and run for 20hours on the same conventional gasoline which however in this runcontained tris (trifiuoroethyl) phosphate in an amount corresponding to0.4 gram atom of phosphorus per 3 gram atoms of lead, i.e. 0.002 gramatom of phosphorus per gallon of gasoline. The octane requirement of theengine increased from 62 to 63, an increase of only one number.

Each type of run was repeated a number of times in a randomized orderwith the ORI determined each time and with disassembly, cleaning andreassembly of the engine between each run. The results of these runs areset forth in Table I.

Table I tris (tritriethyl tris (trifluoroethyl) phosphate, fluoroethyl)Blank phosphate, 0.005 gram phosphate, Additive fuel, no 0.005 gramatoms of P 0.002 gram additive atoms of P per gallon atoms of P pergallon per gallon Octane Requirement Increase.

woooomeaeo Ave. OBI 8. 5

These data show that it is necessary to have the fluorine present in thecompound to reduce CR1 and that better results are obtained when theconcentration level is at 0.002 gram atom of phosphorus per gallon thanwhen it is above this amount. Additional tests have demonstrated that ifthe ratio of phosphorus in the organofluoro phosphorus compound is below0.02 gram atom to 3 gram atoms of lead in the form of lead tetraethyl inthe gasoline this is not enough additive to provide the improvementsdesired according to the invention and correspondingly if the ratio ofphosphorus to lead is in excess of 2 gram atoms of phosphorus to 3 gramatoms of lead no further improvement in engine performance is noted.

EXAMPLE II The same fuel and additive combinations employed in ExampleI, with the exception of the triethyl phosphate additive combination,were employed in a series of 100 hour runs in. the same test engine usedin Example I. The initial octane requirement of the engine wasdetermined before the start of the test run and the octane requirementafter each hours of operation. The engine was not disassembled andcleaned until it had operated for the entire 100 hours. The results ofthose tests are shown in Table II.

Table II tris (trifiuoroethyl) phostris (trifiuoroethyl) phos- AdditiveBlank fuel,No Additive phate,0.005 gram atoms phate,0.002 gram atoms ofP per gallon of P per gallon Time in Hours O 20 0 I20 4O 60 801100 0 204O 60 80 100 Octane Requirement:

gallon of gasoline. The triethyl phosphate corresponds in structure tothe tris (trifluoroethyl) phosphate except These data show that theoctane requirement of the 75 engine increases to a equilibrium valuewith all fuels and that if the additives of the instant invention areemployed, the equilibrium value of the octane requirement of the engineis lower than that of a fuel not containing the additives of theinvention.

EXAMPLE III In order to demonstrate the effectiveness of the fuels ofthis invention in providing reduced ORI and surface ignition under roadtest conditions several compositions of this invention were tested in astock 1957 Oldsmobile 88 with a 9.5 to 1 compression ratio engine undernormal city-suburban driving. After 1500 miles of operation using acommercial gasoline containing 3 cc. tetraethyl lead per gallon and acommercial organo phosphorus-containing additive without fluorine at thelevel of 0.002 gram atom of phosphorus per gallon of gasoline the octanerequirement of the test engine was found to be 96.0.

After completely cleaning the engine of deposits and operating for 1500miles on the same gasoline as above except that instead of thecommercial phosphorus additive it contained 0.002 gram atom ofphosphorus as tris (trifluoroethyl) phosphate the octane requirement wasfound to be 94.0.

The level of surface ignition of the engine also was found to beconsiderably lower when using the fuel containing the tris(trifluoroethyl) phosphate than when using fuel containing the samephosphorus level but without fluorine being present in the additive.

These tests demonstrated that the organofluoro phosphorus compounds ofthe instant invention are superior additives for providing reducedoctane requirement increase and for inhibiting surface ignition ascompared with additives which contain no fluorine and only an organophosphorus compound.

We claim:

1. A gasoline motor fuel consisting essentially of hydrocarbons boilingin the gasoline range and containing tetraethyl lead antiknock agenttogether with an organofluoro phosphorus compound in an amountcorresponding to from 0.02 to 2.0 gram atoms of phosphorus to 3 gramatoms of lead, the organofluoro phosphorus compound having the generalformula:

RaO wherein R R and R are radicals selected from the group consisting ofalkyl, aryl, alkaryl, aralkyl, fluoroalkyl, fluoro-alkaryl andfluoro-aralkyl, the total number of carbon atoms in the molecule rangesbetween 3 and 30, the total number of fluorine atoms in the moleculeranges between 2 and 15 and each fluorine substituted carbon atom has atleast two fluorine atoms attached thereto.

2. A gasoline motor fuel consisting essentially of hydrocarbons boilingin the gasoline range and containing tetraethyl lead antiknock agenttogether with tris (trifluoroethyl) phosphate in an amount correspondingto from 0.02 to 2.0 gram atoms of phosphorus to 3 gram atoms of lead.

3. A gasoline motor fuel consisting essentially of hydrocarbons boilingin the gasoline range and containing tetraethyl lead anti'knock agenttogether with tris (trifluoroethyl) phosphate in an amount correspondingto from 0.2 to 1.0 gram atom of phosphorus to 3 gram atoms of lead.

4. A gasoline motor fuel consisting essentially of hydrocarbons boilingin the gasoline range and containing tetraethyl lead antiknock agenttogether with tris (trifiuoroethyl) phosphate in an amount correspondingto from 0.3 to 0.5 gram atom of phosphorus to 3 gram atoms of lead.

References Cited in the file of this patent UNITED STATES PATENTS2,833,635 Hill et al May 6, 1958 2,834,798 Hechenbleikner et al. May 13,1958 2,839,563 Hechenbleikner June 17, 1958 2,892,691 Howell June 30,1959 FOREIGN PATENTS 1,094,828 France Dec. 15, 1954 1,100,185 FranceMar. 30, 1955 1,134,156 France Nov. 26, 1956 683,405 Great Britain Nov.26, 1952 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION PatentNO. 300K783 November 7 l96l William S. Young et al= d that error appearsin the above numbered pat- It is hereby certifie said Letters Patentshould read as ent requiring correction and that the corrected belowoColumn 3', lines 3 to 6 the formula should appear as shown below insteadof as in the patent:

CF CH O CH CH O-P:O

CF CH O lines 7 to 10 the formula should appear as same column 3,

as in the patent:

shown below instead of CH CI-I O CF CH O P G CH CH O lines 17 to 2O theformula should appear as same column 3,

d of as in the patent:

shown below instea CH CF O CH CH O-P O CH CH O Signed and sealed this17th day of April 1962 Attest:

DAVID L. LAIDD Commissioner of Patents ESTON. G. JOHNSON AttestingOfficer

1. A GASOLINE MOTOR FUEL CONSISTING ESSENTIALLY OF HYDROCARBONS BOILINGIN THE GASOLINE RANGE AND CONTAINING TETRAETHYL LEAD ANTIKNOCK AGENTTOGETHER WITH AN ORGANOFLUORO PHOSPHORUS COMPOUND IN AN AMOUNTCORRESPONDING TO FORM 0.02 TO 2.0 GRAM ATOMS OF PHOSPHORUS TO 3 GRAMATOMS OF LEAD, THE ORGANOFLUORO PHOSPHORUS COMPOUND HAVING THE GENERALFORMULA: